1. Field of Invention
This invention relates generally to network communications systems, and more specifically to network communications systems utilizing LAN and/or WAN configurations.
2. Art Background
Use of computer-based communication networks, wherein two or more computers are operatively linked together via a physical medium such as a cable or via a wireless connection, is widespread. Typically, computer networks are classified according to their geographical size. Local Access Networks (LANs) are the smallest of the networks, and are characterized by small geographical footprints. LANs are primarily used to link computers within an office, although they may be used to link adjacent office buildings. Metropolitan Area Networks (MAN's) are the next largest type of network, and typically operate at the city or regional level using Synchronous Optical Network (SONET) architecture and technology, which is well known in the art as a standard for connecting fiber optic transmission systems. Wide Area Networks (WANs) span the greatest geographical distances, often encompassing entire continents or countries. SONET has an international equivalent, standardized by the International Telecommunications Union (ITU), called Synchronous Digital Hierarchy (SDH). SDH defines a standard rate of transmission at 155.52 Mbps, which is referred to as STS-3 at the electrical level and STM-1 for SDH. STM-1 is equivalent to SONET's Optical Carrier (OC) level 3.
Prior art LANs are structured around an Ethernet protocol, which uses a bus or star topology capable of supporting data transfer rates of up to approximately 10 Mega bits per second (Mbps). Newer versions of Ethernet, called 100Base-T (or Fast Ethenet) or Gigabit Ethernet, support data transfer rates of 100 Mbps and 1 gigabit (1,000 megabits) per second.
Communication problems occur when LAN-configured devices attempt to communicate with WAN-configured devices, and vice versa, because LANs and WANs transmit data at different rates. The differences in data transfer rates result, in part, from the development of new data transmission standards for 10 Gigabit Ethernet, and from the existing SONET infrastructure underlying most WANs.
For example, a first node might be configured to communicate at 10 Mbps, while a second node might be configured to selectively communicate at 10 Mbps, 100 Mbps, or 1,000 Mbps. If the second node attempts to communicate with the first node at 100 Mbps or 1,000 Mbps, the handshake will be unsuccessful because the first node lacks the bandwidth necessary to process the information.
Institute of Electrical and Electronics Engineers (IEEE) standard 802.3 was proposed to delineate an auto-negotiation method whereby the first and second nodes could agree on what data rate to use when communicating with each other. The IEEE auto-negotiation method uses a mechanism such as link pulses to advertise, from both directions, the data rates each node is capable of adopting. The data rates are then compared to find the highest common denominator, and one or more of the nodes are reconfigured to use the shared data rate.
In the above example, link pulses associated with the first node indicate that the node transmits data at 10 Mbps. Similarly, link pulses associated with the second node indicate that it can transmit data at 10 Mbps, 100 Mbps, or 1000 Mbps. In this scenario, comparing the data rates reveals a highest common denominator of 10 Mbps. Accordingly, the second node will transmit data to and receive data from the first node at the 10 Mbps data rate, such that communication between the nodes continues as normal.
It should be noted that this prior art method, being a fixed scheme, does not actually look at the wire (or fiber) linking the two nodes to see at what speeds the data is being transmitted. Instead, each node advertises its transmission capabilities via commonly understood link signals transmitted back and forth between the nodes.
A solution is needed that automatically configures one or more devices residing in separate communication networks to communicate with each other when otherwise the devices would not. Another solution is needed that allows a manufacturer to build single devices addressing both the LAN and WAN 10 Gigabit Ethernet spaces. Yet another solution is needed that reduces the number of port types a user has to consider when attempting to link together two or more devices residing in separate communications networks.